Drying equalizer arrangement



Nov. 3, 1959 w. K. METCALFE I 2,910,784

DRYING EQUALIZER ARRANGEMENT Filed Oct. 10, 1957 5 Sheets-Sheet l INVENTOR.

William xrmetmwa ATTORNEYB Nov. 3, 1959 w. K. METCALFE I 2,910,784

DRYING EQUALIZERARRANGEMENT Filed Oct. 10, 1957 3 Sheets-Sheet 2 7- INVENTOR. ,l

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DRYING EQUALIZER ARRANGEMENT Filed Oct. 10, 1957 3 Sheets-Sheet 3 INVENTOR.

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ATTORNEY 5 United States Patent DRYING EQUALIZER ARRANGEMENT William K. Metcalfe, Chappaqua, N.Y., assignor to Midland-Ross Corporation, a corporation of Ohio Application October 10, 1957, Serial No. 689,295

3 Claims. (Cl. 334-114) This invention relates to drying arrangements for paper machines and more particularly to the drying of a very wide web of sheet material such as paper, cardboard, pulp or the like which is carried over a series of cylinders in a drying machine. The invention particularly concerns itself with equalization of drying conditions so that uniformity of drying is effected.

In paper making machinery, air is used as the vehicle to carry away the moisture liberated in the drying process as the paper sheet passes through the drying section. Since this air is of necessity drawn from outdoors and the leaving exhaust temperature is always different from atmospheric temperature, it is necessary to heat it prior to use. Obviously, therefore, economy demands that the quantity of air be kept to a minimum.

In the past, means have been devised including specially constructed hoods so that initial requirements of 75 to 80 tons of air per ton of paper have been reduced to 25 to 30 tons of air per ton of paper. The drying art has developed into a science of properly exhausting and supplying the relatively large quantities of requisite air.

It has been determined that conditions around the machine itself are important factors and that at least three considerations in and around the paper machine itself are involved. One is air to the machine, another is air away from the machine and the third is the use of air on the machine itself either as applied on felts, on the sheet or in the pockets formed by the sheet as it passes over the dryer section of the machine. It is generally believed that in a two deck paper machine, approximately 75% to 90% of the drying takes place in the said pockets. It is important, therefore, to maintain the most favorable air conditions in and around this region.

' An earlier patent to Grewin No. 1,631,026 discloses a manner of drying a web utilizing thin currents of compressed fluid such as air directed at high speed parallel to the surface to be dried in pockets but at a substantial distance therefrom so that the currents do not impinge upon the surface. A second fluid, such as atmospheric air, is caused by the ejector action of said first current of fluidto pass between said current and said surface in the. pockets to dry the surface. In another embodiment of the Grewin patent, atmospheric air is induced into a high pressure stream within a directing tube and then the pressure air and induced air are caused to pass close to and parallel to the drying surface in the pockets at high speed. The systems disclosed by this Grewin patent are found to work well for webs of medium widths and where the pockets have limited cross sectional area. However, in modern practice webs have become very much wider and the cross sectional area of the pockets of necessity much greater. With such increasing widths, and increased cross section areas of the pockets, the Grewin system has not been found as effective as is desirable.

The air entrainment phenomena and drying action resulting from the use of Grewin system are adequate provided the air pocket into which the air is injected is short "ice and small enough in cross sectional area. However, if the length and areas of the air pocket are increased, as they will be with wider webs going to widths as high as 350 inches, the use of the Grewin air injector system instead of inducing air at the entrance of the pocket to carry the whole mass of air through the pocket will cause the air merely to churn vapors about 4 feet inside of the pocket. No mass movement of vapors is apparent.

It is not possible to install multiple nozzles or larger nipple orifices or to provide greater volumes of air with Grewin systems because if this is attempted, the paper sheet passing over the dryers starts to ripple, forming wrinkles which are of course to be prevented and avoided. Limits, therefore, to the use of the Grewin arrangements are the maximum pressure or quantity of air or both that can be supplied to the end of a pocket without causing objectionable flutter or ripple formation on the web passing through the dryer. In fact it is found that with current greater web widths, it has become impossible to use the Grewin system effectively in some cases.

Principal objects and features of this invention are the provision of air flow equalizer arrangements for paper making machines particularly those having very wide webs so that uniformity of drying is effected.

Additional objects and features of the invention are provision of air flow equalization for the machines that can be readily installed both in new and existing structures without requiring complex installation procedure or reconstruction or remodification of existing machines.

Still further objects and features of the invention will become apparent from the following description and the accompanying drawings wherein:

Figure 1 is a diagrammatic side elevation of a two stack dryer section of a paper machine;

Figure 2 is a vertical transverse section taken generally along line 2-2 of Figure 4 of the dryer section of a paper making machine embodying the invention showing the arrangement of the machine with respect to the floor and basement of the structure in which it is housed and also the relationship of the air exhausting hood with respect to the machine;

Figure 3 is a view taken .along the line 33 of Figure 2;

Figure 4 is a view taken along line 4-4 of Figure 2; and

Figure 5 is an enlarged fragmentary View of a portion of the components shown in Figure 2 for clarity of detail.

Referring now to the drawings, the reference character 11 denotes generally the dryer section of a web drying machine. This dryer section in the embodiment shown is a so-called two stack dryer including an upper set of drying cylinders 12 and a lower set of drying cylinders 13 having a web 14 passing around them. An upper felt 15 passes over the upper cylinders 12 and around idler rollers 16. Similarly, a lower felt 17 passes around cylinders 13 and idler rollers 13. The cylinders 12 and 13 are heated in conventional ways.

The arrangement of cylinders, webs, and felts provides a series of pockets or spaces extending laterally or transversely of the web drying machine, some of these pockets or spaces 19a being defined between the sides determined by the web 14, the lower cylinders 13 and the upper felt 15, while other pockets or spaces 1% are defined between sides determined by the web 14, the upper cylinders 12 and the lower felt 17, and still other pockets or spaces 19c are defined by the felt 17 and idler rollers 18.

As seen in Figure 2, the web 14 at other portions of the machine also passes around other rollers or cylinders 21 which are positioned in a basement 22 or space below the floor 23 of the building housing the machine. A

:3 suitable floor opening 24 is provided in the floor 23 for this purpose. The floor opening 24, as seen in Figures 2 and 5, is somewhat wider than the cylinders 12, 13 and 21 and in fact the lower parts of cylinders 13 are partially submerged below the upper surface of the floor 23 and within opening 24.

It is intended that air for use in the dryer section be derived from the basement 22 or space below floor 23 passing upwardly therefrom through available passageways 25 and 26 provided respectively in the opening 24 adjacent opposite front and rear ends of the partially submerged cylinders 13. These passageways 25 and 26 arethe only ones available for the upward flow of air from the basement through opening 24 because the web 14 blocks off all other portions of the area of the floor opening 24. Since the web 14 and felts 15 and 17 block off upward passage of air and vapors from the basement 22 except through the narrow front and rear passageways 25 and 26, a Venturi-like effect is created in the flow paths from the basement through the restricted passageways 25 and 26. In other words, passageways 25 and 26 are Venturi-like in nature.

The cylinders 12 and 13 are supported respectively at their front and rear ends by machine frame 27 and gear train housing 28 both fixed to a sole plate 29 secured to the floor adjacent the opening 24. This housing 28 carries intermeshing gears 30 which are utilized to drive or rotate the cylinders 12 and 13, or a chain drive.

As seen in Figure 4, the front frame 27 has open portions 31 and 32 (for weight reduction and ease of operation) which communicate freely with areas of the pockets or spaces 19, 19a, 19b and 190 defined between webs, felts and cylinders as hereinabove mentioned. The rear housing 28 also has open portions 33 and 34. Major areas of the latter, however, are blocked as seen in Figures 3 and 5.

The narrow floor passageways 25 and 26 as above mentioned, effect compression and a Venturi-like effect on air, vapors and gases flowing upwardly from the basement 22 through these passageways 25 and 26. After passage through the Venturi-like passageways 25 and 26, the air vapors tend to expand at the front and rear of the machine. Expansion at the rear, however, is blocked or limited by the gear train housing 28 notwithstanding the existence of the open portions 33 and 34 in the said housing 28. At the front face of the machine, the open portions 31 and 32 in the front frame part 27 ordinarily permit unrestricted expansion. As a result, the flow of air from the basement 22 ordinarily is unsymmetrical because of the free expansion at the exit to Venturi 25 and restricted expansion at the exit to Venturi 26. This creates undesirable cross migrations of air through the pockets or spaces 19a, 19b and 190 from the back toward the front of the machine and across the web and felts. In such migration, the air picks up moisture as it traverses the width of the web from rear to front. In consequence, in a wide web, the front portion of the web will not be as dry as the back portion of the web because the increasingly moist air moving from back to front will have decreasing drying effects.

It is not desirable to eliminate upward passage of air from the basement through the Venturi-like passageways 25 and 26 because a certain quantity of air is required for proper conditioning of the felt 14. However, the cross migration problem caused by the free expansion possible at the front frame must be eliminated. To this end, it is desirable that the front open portions 31 and' 32 of the machine frame part 27 be blocked off in areas corresponding to the open portion areas blocked off by the gear train 3%) in the rear housing 28. One solution would be to make the frame parts 27 and 28 both solid. However, such arrangement wouldrequire material remodification of the frame parts 27 and Z8 and in addition, materially increase their already massive weights. In addition, wide pockets and open frame construction are 4 required to spear broke. In other words, they permit utilization of poles or rods with hooks to clean out the paper if a break occurs and the dryers are wrapped or chunks are lodged in components of the machine.

A more practical and simple solution for the problem is found in the provision of a baffle means or plate 36 shown in section in Figures 2,4 and 5. This bafile means 36 is secured to the sole plate 29 adjacent front frame part 27 and has rolled upper edge 37. The contour of the upper edge preferably is substantially similar to the contour of the gear train housing 28 at least to the level of the line x--x lying coincident substantially with the upper limits just under the heights of the idler rollers 16 and the floor of a catwalk 38 if present. In the alternative, the upper edge may be substantially a straight line lying along line x-x. The lower edge of the baffle 36 lies at the floor line. The baffle 36 extends the full length of the dryer 11. The provision of this baffle 36 which can be readily secured in blocking relationship over the required areas of the open portions 31 and 32 of the front machine frame part 27 provides equalizing expansion conditions to air leaving the front Venturi-like passageway 25 as compared with air leaving the rear Venturi-like passageway 26. In other words, with this baffle 36 in position which results in equalized air expansion at the outlets of the passageways 25 and 26, unbalanced cross migrational tendencies in pockets or spaces 19a, 19b and 19c are eliminated, and the expanding air rising at the mouths of Venturis 25 and 26 the front and rear faces of the machine is withdrawn uniformly by the hood 39. This uniform withdrawal provides equalizing effects and uniform Withdrawal of air from the pockets or spaces 19a, 19b and as illustrated by the directional arrows in Figures 2 and 5. Since substantially uniform withdrawal of air from the pockets or spaces 19a, 19b and 19c is effected, substantially uniform drying of the web and felts across their whole widths occurs, rather than a preferential drying along one edge (the rear) thereof which would occur were cross migration to occur.

In other words, the provision of the baffling arrangement 36 at the front frame part 27 serves to provide air flow conditions of like character for emerging air and gas rising through and leaving the Venturi-like passageways 25 and 26 and effectively solves a problem that cannot be solved merely by blowing air from nozzles from one side or the other and adequately counteract cross flow when very wide webs are processed At the same time, the solution is simple and capable of application not only to existing machines but to new machines without requiring any material modification of parts already existing. Moreover, the installation is simple and relatively inexpensive.

While specific embodiments of the machine have been disclosed, variations in structural detail within the scope of the appended claims are possible andare contemplated. There is no intention, therefore, of limitation to the exact details shown and described.

What is claimed is:

1. In combination with the dryer section of wide web paper making machinery mounted over a floor opening to permit aircirculation upwardly from below the floor opening through restricted Venturi-like passageways defined at the front and rear of the dryer section, front and rear frame parts lying outwardly of said passageways and having open portions and a gear housing closing areas of the open portions of the rear frame part, and baffle means extending substantially the full length of said front frame part and upwardly from the floor opening and positioned adjacent the inner face of the front frame part and covering open. areas in said front frame part to close off those areas in the open portions of the front frame part that correspondto those closed off at the rear frame part by said gear housing so as to provide substantially balanced expansion conditions for upwardly moving gases leaving all said Venturi-like passageways and thereby to effect substantially uniform drying of webs passing through said dryer section.

2. In combination with wide web paper making machinery mounted on a floor to permit circulation therethrough of gas from below the floor through an opening, front and rear frame parts located adjacent the opening, drying cylinders carried by said frame parts, a web passed around the cylinders, some of said cylinders lying partially submerged within said opening and with said web and cylinders defining Venuri-like front and rear passageways through the floor opening adjacent the inner faces of the respective frame parts, said frame parts having similar open portions lying opposite each other, a gear housing blocking off areas of the open portions of the rear frame part, and baflie means extending upwardly from the floor opening adjacent the inner face of the front frame part for substantially the full length of the front frame part for blocking similarly disposed areas of open portions thereof to provide equalized expansion conditions for upwardly moving gases leaving the Venturi-like passageways at both the front and rear of the machine to thereby eliminate unsymmetrical drying effects of gas migrating across the web in pockets defined by the web and cylinders.

3. In combination with wide web paper making machinery mounted on a floor over an opening to permit gas circulation therethrough from below the floor, front and rear frame parts located adjacent the opening, drying cylinders carried by said frame part in at least two superposed tiers with cylinders of the lowermost tier lying partially submerged within said opening, a web passed around the cylinders, and said web and said partially submerged cylinders defining Venturi-like front and rear passageways through the floor opening adjacent the inner faces of the respective front and rear frame parts, said frame parts having similarly disposed open portions lying opposite each other, a gear housing blocking off major areas of the open portions of the rear frame part, and a bafile member extending upwardly from the floor opening and positioned adjacent the inner face of said front frame part for substantially its full length and shaped to block off similarly disposed major areas of the open portions of the front frame part to thus provide equalized expansion conditions for upwardly moving gases leaving the Venturi-like passageways at both the front and rear of the machine to thereby eliminate unsymmetrical drying effects of gas migration across the web in pockets defined by the web and cylinders, said bafiie member having a shaped upper edge.

References Cited in the file of this patent UNITED STATES PATENTS 1,524,507 Christie et a1. Jan. 27, 1925 1,961,182 Williams June 5, 1934 

